1. Field of the Invention
The present invention relates to a power converter that converts AC power into DC power and converts DC power into AC power, and converts voltage.
2. Description of Related Art
A power converter circuit which converts DC power into AC power or converts AC power into DC, that is, an inverter is known. A power converter circuit which raises or lowers a DC voltage, that is, a boost converter is also known. A plurality of power converter circuits which change a characteristic of electric power (AC/DC, voltage, etc.) are sometimes integrally combined to constitute an power converter.
One example of the use of a power converter is in a hybrid vehicle which is equipped with an internal combustion engine and an electric motor as driving sources. A three-phase AC synchronous motor is sometimes used as the electric motor for a hybrid vehicle. The electric motor functions also as a power generator to generate electric power when its rotating shaft is driven by the inertia of the vehicle. In the following description, an electrical device which corresponds to a concept which includes an electric motor, a power generator, and an electrical device which can function as an electric motor and a power generator is referred to as “rotating electric machine.” An inverter is used to drive a rotating electric machine with a DC power source, such as a secondary battery, which is mounted on a vehicle, or to charge a secondary battery with the electric power that is regenerated by the rotating electric machine. A boost converter is sometimes provided to boost the terminal voltage of the secondary battery and supply the boosted voltage to an electric motor. In addition, a hybrid vehicle which is equipped with two rotating electric machines is known, in which case, an inverter is used for each of the two electric motors.
Such a power converter circuit is constituted using semiconductor modules which include IGBT elements, for example. Japanese Patent Application Publication No. 2006-295997 (JP 2006-295997 A) discloses a device in which terminals of a plurality of semiconductor modules which constitutes a power converter are connected by a bus bar.
When a plurality of power converter circuits are combined to constitute a power converter and terminals of semiconductor modules of the power converter circuits are connected by a bus bar, interference may be caused between the power converter circuits by a surge voltage.